/* interface.c*/


#include <stdlib.h>
#include <stdio.h>

#include "common.h"
#include "interface.h"
#include "tabinit.h"
#include "layer3.h"

#include "layer1.h"

#include "layer2.h"


BOOL InitMP3( PMPSTR mp) 
{
	memset(mp, 0, sizeof(MPSTR));

	mp->framesize = 0;
	mp->num_frames = 0;
	mp->enc_delay = -1;
	mp->enc_padding = -1;
	mp->vbr_header=0;
	mp->header_parsed=0;
	mp->side_parsed=0;
	mp->data_parsed=0;
	mp->free_format=0;
	mp->old_free_format=0;
	mp->ssize = 0;
	mp->dsize=0;
	mp->fsizeold = -1;
	mp->bsize = 0;
	mp->head = mp->tail = NULL;
	mp->fr.single = -1;
	mp->bsnum = 0;
	mp->wordpointer = mp->bsspace[mp->bsnum] + 512;
	mp->bitindex = 0;
	mp->synth_bo = 1;
	mp->sync_bitstream = 1;

	mp->quick_dirty=0; //WarpE: normal operation as default

	make_decode_tables(1.0);  //sh0

	init_layer3(SBLIMIT);

	init_layer2();

	return !0;
}

void ExitMP3( PMPSTR mp)
{
	struct buf *b,*bn;
	
	b = mp->tail;
	while(b) {
		free(b->pnt);
		bn = b->next;
		free(b);
		b = bn;
	}
}

static struct buf *addbuf( PMPSTR mp, unsigned char *buf,int size)
{
	struct buf *nbuf;

	nbuf = (struct buf*) malloc( sizeof(struct buf) );
	if(!nbuf) {
		fprintf(stderr,"Out of memory!\n");
		return NULL;
	}
	nbuf->pnt = (unsigned char*) malloc((size_t)size);
	if(!nbuf->pnt) {
		free(nbuf);
		return NULL;
	}
	nbuf->size = size;
	memcpy(nbuf->pnt,buf,(size_t)size);
	nbuf->next = NULL;
	nbuf->prev = mp->head;
	nbuf->pos = 0;

	if(!mp->tail) {
		mp->tail = nbuf;
	}
	else {
	  mp->head->next = nbuf;
	}

	mp->head = nbuf;
	mp->bsize += size;

	return nbuf;
}

void remove_buf(PMPSTR mp)
{
  struct buf *buf = mp->tail;
  
  mp->tail = buf->next;
  if(mp->tail)
    mp->tail->prev = NULL;
  else {
    mp->tail = mp->head = NULL;
  }
  
  free(buf->pnt);
  free(buf);
}

static int read_buf_byte(PMPSTR mp)
{
	unsigned int b;
	int pos;

	pos = mp->tail->pos;
	while (pos >= mp->tail->size) {
		remove_buf(mp);
		if (!mp->tail) {
			fprintf(stderr, "Fatal error! tried to read past mp buffer\n");
//			exit(1); // no exit here in MPASource
		}
		pos = mp->tail->pos;
	}

	b = mp->tail->pnt[pos];
	mp->bsize--;
	mp->tail->pos++;

	return b;
}



static void read_head(PMPSTR mp)
{
	unsigned long head;

	head = read_buf_byte(mp);
	head <<= 8;
	head |= read_buf_byte(mp);
	head <<= 8;
	head |= read_buf_byte(mp);
	head <<= 8;
	head |= read_buf_byte(mp);

	mp->header = head;
}


static int ii;

static void copy_mp(PMPSTR mp, int size, unsigned char *ptr)
{
	int len = 0;

	ii++;
	if (size>=MAXFRAMESIZE)
	{
		return;
	}
	while (len < size && mp->tail) {
		int nlen;
		int blen = mp->tail->size - mp->tail->pos;
		if ( (size - len) <= blen) {
			nlen = size-len;
		}
		else {
			nlen = blen;
		}
		memcpy(ptr+len, mp->tail->pnt + mp->tail->pos, (size_t)nlen);
		len += nlen;
		mp->tail->pos += nlen;
		mp->bsize -= nlen;
		if (mp->tail->pos == mp->tail->size) {
			remove_buf(mp);
		}
	}
}

/* number of bytes needed by GetVbrTag to parse header */
#define XING_HEADER_SIZE 194

/* traverse mp data structure without changing it */
/* (just like sync_buffer) */
/* pull out Xing bytes */
/* call vbr header check code from LAME */
/* if we find a header, parse it and also compute the VBR header size */
/* if no header, do nothing. */
/* */
/* bytes = number of bytes before MPEG header.  skip this many bytes */
/* before starting to read */
/* return value: number of bytes in VBR header, including syncword */
static int check_vbr_header(PMPSTR mp,int bytes)
{
  int i,pos;
  struct buf *buf=mp->tail;
  unsigned char xing[XING_HEADER_SIZE];
//  VBRTAGDATA pTagData; Warp

  pos = buf->pos;
  /* skip to valid header */
  for (i=0; i<bytes; ++i) {
    while(pos >= buf->size) {
      buf  = buf->next;
      pos = buf->pos;
      if(!buf) 	return -1; /* fatal error */
    }
    ++pos;
  }
  /* now read header */
  for (i=0; i<XING_HEADER_SIZE; ++i) {
    while(pos >= buf->size) {
      buf  = buf->next;
      pos = buf->pos;
      if(!buf) 	return -1; /* fatal error */
    }
    xing[i] = buf->pnt[pos];
    ++pos;
  }

  /* check first bytes for Xing header */
//  mp->vbr_header = GetVbrTag(&pTagData,xing);
  mp->vbr_header = 0; //Warp
/*  if (mp->vbr_header) {
    mp->num_frames=pTagData.frames;
    mp->enc_delay=pTagData.enc_delay;
    mp->enc_padding=pTagData.enc_padding;

    return pTagData.headersize;
  }
*/
  return 0;
}


static int sync_buffer(PMPSTR mp, int free_match)
{
	/* traverse mp structure without modifing pointers, looking
	* for a frame valid header.
	* if free_format, valid header must also have the same
	* samplerate.   
	* return number of bytes in mp, before the header
	* return -1 if header is not found
	*/
	unsigned int b[4]={0,0,0,0};
	int i,h,pos;
	struct buf *buf=mp->tail;
	if (!buf) return -1;

	pos = buf->pos;
	for (i=0; i<mp->bsize; i++) {
		/* get 4 bytes */
		b[0]=b[1]; b[1]=b[2]; b[2]=b[3];

		while(pos >= buf->size) {
			buf  = buf->next;
			pos = buf->pos;
			if(!buf) {
				return -1;
				/* not enough data to read 4 bytes */
			}
		}
		b[3] = buf->pnt[pos];
		++pos;

		if (i>=3) {
			struct frame *fr = &mp->fr;
			unsigned long head;

			head = b[0];
			head <<= 8;
			head |= b[1];
			head <<= 8;
			head |= b[2];
			head <<= 8;
			head |= b[3];
			h = head_check(head, fr->lay);

			if (h && free_match) {
				/* just to be even more thorough, match the sample rate */
				int mode, stereo, sampling_frequency, mpeg25, lsf;

				if( head & (1<<20) ) {
					lsf = (head & (1<<19)) ? 0x0 : 0x1;
					mpeg25 = 0;
				}
				else {
					lsf = 1;
					mpeg25 = 1;
				}

				mode   = ((head>>6)&0x3);
				stereo = (mode == MPG_MD_MONO) ? 1 : 2;

				if (mpeg25)
					sampling_frequency = 6 + ((head>>10)&0x3);
				else
					sampling_frequency = ((head>>10)&0x3) + (lsf*3);
				h = ((stereo==fr->stereo) && (lsf==fr->lsf) && (mpeg25==fr->mpeg25) && 
				(sampling_frequency == fr->sampling_frequency));
			}

			if (h) {
				return i-3;
			}
		}
	}
	return -1;
}



int decodeMP3(PMPSTR mp, unsigned char *in, int isize, char *out, int osize, int *done)
{
	int i,iret,bits,bytes;

	if (osize < 4608) {
		fprintf(stderr,"To less out space\n");
		return MP3_ERR;
	}

	if (in) {
		if(addbuf(mp,in,isize) == NULL) {
			return MP3_ERR;
		}
	}


	/* First decode header */
	if (!mp->header_parsed) {

		if (mp->fsizeold==-1 || mp->sync_bitstream) {
			int vbrbytes;
			mp->sync_bitstream = 0;

		   /* This is the very first call. sync with anything */
			/* bytes= number of bytes before header */
			bytes = sync_buffer(mp, 0); 

			/* now look for Xing VBR header */
			if (mp->bsize >= bytes+XING_HEADER_SIZE ) {
		   /* vbrbytes = number of bytes in entire vbr header */
				vbrbytes=check_vbr_header(mp,bytes);
			} else {
		    /* not enough data to look for Xing header */
				return MP3_NEED_MORE;
			}

			if (mp->vbr_header) {
				/* do we have enough data to parse entire Xing header? */
				if (bytes+vbrbytes > mp->bsize) return MP3_NEED_MORE;
		    
				 /* read in Xing header.  Buffer data in case it
				  * is used by a non zero main_data_begin for the next
				  * frame, but otherwise dont decode Xing header */

				/*fprintf(stderr,"found xing header, skipping %i bytes\n",vbrbytes+bytes);*/
		   
				for (i=0; i<vbrbytes+bytes; ++i) read_buf_byte(mp);
				/* now we need to find another syncword */
				/* just return and make user send in more data */
				return MP3_NEED_MORE;
			}
		} else {
			/* match channels, samplerate, etc, when syncing */
			bytes = sync_buffer(mp,1);
		}

		if (bytes<0) return MP3_NEED_MORE;

		if (bytes>0) {
			/* there were some extra bytes in front of header.
			* bitstream problem, but we are now resynced 
			* should try to buffer previous data in case new
			* frame has nonzero main_data_begin, but we need
			* to make sure we do not overflow buffer
			*/
			int size;
			fprintf(stderr,"bitstream problem: resyncing...\n");
			mp->old_free_format=0;
			mp->sync_bitstream=1;

			/* skip some bytes, buffer the rest */
            size = (int) (mp->wordpointer - (mp->bsspace[mp->bsnum]+512));
			
			if (size > MAXFRAMESIZE) {
				/* wordpointer buffer is trashed.  probably cant recover, but try anyway */
				fprintf(stderr,"mpglib: wordpointer trashed.  size=%i (%i)  bytes=%i \n", size, MAXFRAMESIZE, bytes);
				size=0;
                mp->wordpointer = mp->bsspace[mp->bsnum]+512;
			}
			
			/* buffer contains 'size' data right now 
				we want to add 'bytes' worth of data, but do not 
				exceed MAXFRAMESIZE, so we throw away 'i' bytes */
			i = (size+bytes)-MAXFRAMESIZE;
			for (; i>0; --i) {
				--bytes;
				read_buf_byte(mp);
			}
			
			copy_mp(mp, bytes, mp->wordpointer);
			mp->fsizeold += bytes;
		}
	    
		read_head(mp);
		decode_header(&mp->fr, mp->header);
		mp->header_parsed=1;
		mp->framesize = mp->fr.framesize;
		mp->free_format = (mp->framesize==0);

		if(mp->fr.lsf)
			mp->ssize = (mp->fr.stereo == 1) ? 9 : 17;
		else
			mp->ssize = (mp->fr.stereo == 1) ? 17 : 32;
		
		if (mp->fr.error_protection) 
			mp->ssize += 2;

		mp->bsnum = 1-mp->bsnum; /* toggle buffer */
        mp->wordpointer = mp->bsspace[mp->bsnum] + 512;
        mp->bitindex = 0;

		/* for very first header, never parse rest of data */
		if (mp->fsizeold==-1)
			return MP3_NEED_MORE;
	}
	
	/* now decode side information */
	if (!mp->side_parsed) {

		/* Layer 3 only */
		if (mp->fr.lay==3)
		{
			if (mp->bsize < mp->ssize) 
				return MP3_NEED_MORE;

            copy_mp(mp, mp->ssize, mp->wordpointer);

			if (mp->fr.error_protection)
                getbits(mp, 16);
            bits = do_layer3_sideinfo(mp);
			/* bits = actual number of bits needed to parse this frame */
			/* can be negative, if all bits needed are in the reservoir */
			if (bits<0) bits=0;

			/* read just as many bytes as necessary before decoding */
			mp->dsize = (bits+7)/8;

			/* this will force mpglib to read entire frame before decoding */
			/* mp->dsize= mp->framesize - mp->ssize;*/

		}
		else
		{
			/* Layers 1 and 2 */

			/* check if there is enough input data */
			if (mp->fr.framesize > mp->bsize)
				return MP3_NEED_MORE;

			/* takes care that the right amount of data is copied into wordpointer */
			mp->dsize=mp->fr.framesize;
			mp->ssize=0;
		}

		mp->side_parsed=1;
	}

	/* now decode main data */
	iret=MP3_NEED_MORE;
	if (!mp->data_parsed ) {
		if (mp->dsize > mp->bsize) {
			return MP3_NEED_MORE;
		}

        copy_mp(mp, mp->dsize, mp->wordpointer);

		*done = 0;

		/*do_layer3(&mp->fr,(unsigned char *) out,done); */
		switch (mp->fr.lay)
		{
			case 1:
				if (mp->fr.error_protection)
                getbits(mp, 16);

                do_layer1(mp,(unsigned char *) out, done);
				break;

			case 2:
				if (mp->fr.error_protection)
                getbits(mp, 16);

                do_layer2(mp,(unsigned char *) out, done);
				break;

			case 3:
                do_layer3(mp,(unsigned char *) out, done);
				break;
		
			default:
                fprintf(stderr, "invalid layer %d\n", mp->fr.lay);
		}

        mp->wordpointer = mp->bsspace[mp->bsnum] + 512 + mp->ssize + mp->dsize;

		mp->data_parsed=1;
		iret=MP3_OK;
	}


	/* remaining bits are ancillary data, or reservoir for next frame 
	 * If free format, scan stream looking for next frame to determine
	 * mp->framesize */
	if (mp->free_format)
	{
		if (mp->old_free_format) {
			/* free format.  bitrate must not vary */
			mp->framesize=mp->fsizeold_nopadding + (mp->fr.padding);
		} else {
			bytes=sync_buffer(mp,1);
			if (bytes<0) return iret;
			mp->framesize = bytes + mp->ssize+mp->dsize;
			mp->fsizeold_nopadding= mp->framesize - mp->fr.padding;
		/*
		fprintf(stderr,"freeformat bitstream:  estimated bitrate=%ikbs  \n",
		8*(4+mp->framesize)*freqs[mp->fr.sampling_frequency]/
		(1000*576*(2-mp->fr.lsf)));
		*/
		}
	}

	/* buffer the ancillary data and reservoir for next frame */
	bytes = mp->framesize-(mp->ssize+mp->dsize);
	if (bytes > mp->bsize) {
		return iret;
	}

	if (bytes>0)
	{
		int size;

        copy_mp(mp, bytes, mp->wordpointer);

        mp->wordpointer += bytes;

        size = (int) (mp->wordpointer - (mp->bsspace[mp->bsnum]+512));
		if (size > MAXFRAMESIZE) {
			fprintf(stderr, "fatal error.  MAXFRAMESIZE not large enough.\n");
		}
	}

	/* the above frame is completey parsed.  start looking for next frame */
	mp->fsizeold = mp->framesize;
	mp->old_free_format = mp->free_format;
	mp->framesize =0;
	mp->header_parsed=0;
	mp->side_parsed=0;
	mp->data_parsed=0;

	return iret;
}